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Mar 29, 2013 | 8:12 AM (Photo: Reuters/David Manning)Neighborhood watch volunteer George Zimmerman (L) leaves the Seminole County Jail after posting bail in Sanford, Fla., April 22, 2012. Zimmerman, standing trial on a charge of second-degree murder in the death of unarmed black teenager Trayvon Martin, was granted 0,000 bail by a judge on Friday.

George Zimmerman's attorney is reportedly concerned that recent tweets posted by his client's brother could hurt his defense in the Trayvon Martin case.

Zimmerman's brother Robert, who has desperately defended him via media and Twitter, is now backtracking on a series of tweets targeting Martin. In 2012, Martin, who was 17 at the time of his death, was shot and killed by 28-year-old Zimmerman, who has subsequently been charged with second-degree murder.

"I made a mistake," Robert Zimmerman Jr. said during an appearance on CNN's Piers Morgan Live. "It unfortunately may not have helped George."

In one tweet, Robert posted a photograph of Martin alongside one of 17-year-old De'Marquise Elkins, one of two teenagers charged with killing a baby in Georgia. The African-American teens appear to be flipping off the camera in their individual photos.

"A picture speaks a thousand words. Any questions?" Robert tweeted to his 3,000 followers.

In another tweet, Robert posted: "Lib media shld ask if what these2 black teens did 2 a woman&baby is the reason ppl think blacks mightB risky."

Prosecutors claim Zimmerman, who was a volunteer neighborhood watch captain in Florida, profiled Martin, who was dressed in a hooded sweatshirt and found with no weapons after being killed. Mark O'Mara, who represents Zimmerman, maintains that his client was simply defending himself after he was allegedly attacked by the unarmed teen and he recently addressed Robert's tweets.

"Having said that, I'm not sure where (Robert's) heart was, but I've always said for the past year that we have to have a conversation about race, and the Zimmerman case has brought it to the forefront, particularly the way young black males are treated in the system," O'Mara said Thursday on CNN's "Starting Point."

"These type of tweets ... were insensitive to that, and quite honestly are the opposite of what I hope the conversation would be to try and figure out what's wrong with the system and maybe a good way to fix it," he continued. "And certainly when a family member of my client says something that comes across as totally insensitive-- if not much, much worse-- [it] has an effect, and now we have to deal with it."